Wildfires in Canada have roared back to life, sending harmful smoke into the northern United States — an unwelcome reminder of last summer’s historic fire season that also repeatedly sent plumes of noxious haze southward.

Almost a year to the date from the explosive start to the 2023 fire season, hundreds of fires have erupted in Canada, including a dozen major and out-of-control blazes. At least 500,000 acres (200,000 hectares) of land have burned so far, much of it in recent days.

Canada's wildfire season has erupted as dozens of blazes burn in the country's western provinces, and smoke from those fires is choking the skies over the Upper Midwest early this week.

The Twin Cities of Minneapolis-St. Paul in Minnesota claimed the worst air quality in America on Monday after winds carried the smoke southeastward into the northern U.S.

Hazy skies were first seen Sunday over parts of northern Minnesota before spreading farther south into the Twin Cities overnight.

Central and northern Wisconsin are under an air quality advisory due to Canadian wildfire smoke, according to the National Weather Service in Sullivan.

In those portions of the state, people can see smoke in the sky, and in some areas, on ground level, said Mark Gehring, NWS meteorologist.

Visibilities are ranging from 4 to 7 miles in parts of west central and northern Wisconsin, as well as southern Minnesota, Gehring said.